U.S. patent application number 11/593543 was filed with the patent office on 2007-05-10 for method of forming pattern.
This patent application is currently assigned to NEC ELECTRONICS CORPORATION. Invention is credited to Yukiya Kawakami.
Application Number | 20070105051 11/593543 |
Document ID | / |
Family ID | 38004149 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070105051 |
Kind Code |
A1 |
Kawakami; Yukiya |
May 10, 2007 |
Method of forming pattern
Abstract
Formation of a constricted portion in an interconnect pattern is
inhibited while moderating design rule for a phase shifting mask.
When an interconnect pattern including a plurality of straight
lines that are arranged in parallel is formed in a photoresist film
on or over a wafer, the process thereof comprises: providing
different phase apertures 114 and 116 in longitudinal external side
of the interconnect apertures 110 and 112 in the phase shifting
mask 100, the different phase aperture providing a phase of light
that is different from a phase of light through the interconnect
apertures 110 and 112; transferring a basic pattern in the
photoresist film via an exposure by using the phase shifting mask
100, the basic pattern containing the interconnect pattern and a
temporary pattern formed from an end of the interconnect pattern
toward a longitudinal external side thereof; and transferring a
temporary pattern in the photoresist for removing the temporary
pattern from the basic pattern via an exposure by using a trim
mask.
Inventors: |
Kawakami; Yukiya; (Kawasaki,
JP) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET
2ND FLOOR
ARLINGTON
VA
22202
US
|
Assignee: |
NEC ELECTRONICS CORPORATION
Kanagawa
JP
|
Family ID: |
38004149 |
Appl. No.: |
11/593543 |
Filed: |
November 7, 2006 |
Current U.S.
Class: |
430/311 ;
430/5 |
Current CPC
Class: |
G03F 1/70 20130101; G03F
7/70283 20130101; G03F 7/70466 20130101; G03F 1/30 20130101 |
Class at
Publication: |
430/311 ;
430/005 |
International
Class: |
G03F 7/20 20060101
G03F007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 8, 2005 |
JP |
2005-323604 |
Claims
1. A method of forming a pattern, in which an interconnect pattern
including a plurality of straight lines that are arranged in
parallel is formed in a photoresist film on or over a wafer by
exposing thereof to light through a phase shifting mask, said phase
shifting mask having interconnect apertures that extend toward a
predetermined direction and are arranged in parallel, and said
phase shifting mask also being configured that transmitted lights
of two different phases are alternately assigned in the
interconnect aperture, said method comprising: providing a
different phase aperture in a longitudinal external side of said
interconnect aperture in said phase shifting mask, said different
phase aperture providing a phase of transmitted light that is
different from a phase of light through the interconnect aperture;
transferring a basic pattern in a photoresist film via an exposure
by using said phase shifting mask, said basic pattern containing
said interconnect pattern and a temporary pattern formed from an
end of said interconnect pattern toward a longitudinal external
side thereof; and transferring a temporary pattern in a photoresist
film for removing said temporary pattern from said basic pattern
via an exposure by using a trim mask.
2. The method of forming a pattern according to claim 1, wherein
said phase shifting mask includes a peripheral opaque region in a
longitudinal external side of said interconnect aperture, and said
different phase aperture is formed in said peripheral opaque
region.
3. The method of forming a pattern according to claim 1, wherein
said phase shifting mask includes a peripheral exposure region in a
longitudinal external side of said interconnect aperture, and said
different phase aperture is disposed in said peripheral exposure
region.
4. The method of forming a pattern according to claim 3, wherein a
light of one phase in two inverse-phase lights is assigned in said
peripheral exposure region, and wherein said peripheral exposure
region forms said different phase aperture of the interconnect
aperture around the longitudinal direction of said interconnect
aperture, for which light of the other phase is assigned.
5. The method of forming a pattern according to claim 1, wherein
said phase shifting mask is configured that said different phase
apertures, which are disposed in a mutually adjacent relationship,
are continually arranged.
6. The method of forming a pattern according to claim 1, wherein
said phase shifting mask is arranged continually with said
different phase apertures, which is configured that at least one of
said interconnect aperture is arranged in a longitudinal external
side of an aperture for interconnect.
7. A method of forming a pattern, in which an interconnect pattern
including a plurality of straight lines that are arranged in
parallel is formed in a sacrificial film on or over a wafer by
exposing thereof to light through a phase shifting mask, said phase
shifting mask having interconnect apertures that extend toward a
predetermined direction and are arranged in parallel, and said
phase shifting mask also being configured that transmitted lights
of two different phases are alternately assigned in the
interconnect aperture, wherein said sacrificial film includes: a
hard mask formed on said wafer; a first photoresist film employed
for etching said hard mask; and a second photoresist film applied
on said wafer after said hard mask is etched through said first
photoresist film, wherein said method comprising: providing a
different phase aperture in a longitudinal external side of said
interconnect aperture in said phase shifting mask, said different
phase aperture providing a phase of transmitted light that is
different from a phase of light through the interconnect aperture;
etching said hard mask by using a mask of said first photoresist
film, on which said basic pattern is transferred; and transferring
a temporary pattern in said second photoresist film for removing
said temporary pattern from said basic pattern via an exposure by
using a trim mask.
8. The method of forming a pattern according to claim 7, wherein
said phase shifting mask includes a peripheral opaque region in a
longitudinal external side of said interconnect aperture, and said
different phase aperture is formed in said peripheral opaque
region.
9. The method of forming a pattern according to claim 7, wherein
said phase shifting mask includes a peripheral exposure region in a
longitudinal external side of said interconnect aperture, and said
different phase aperture is disposed in said peripheral exposure
region.
10. The method of forming a pattern according to claim 7, wherein a
light of one phase in two inverse-phase lights is assigned in said
peripheral exposure region, and wherein said peripheral exposure
region forms said different phase aperture of the interconnect
aperture around the longitudinal direction of said interconnect
aperture, for which light of the other phase is assigned.
11. The method of forming a pattern according to claim 7, wherein
said phase shifting mask is configured that said different phase
apertures, which are disposed in a mutually adjacent relationship,
are continually arranged.
12. The method of forming a pattern according to claim 7, wherein
said phase shifting mask is arranged continually with said
different phase apertures, which is configured that at least one of
said interconnect aperture is arranged in a longitudinal external
side of an aperture for interconnect.
Description
[0001] This application is based on Japanese patent application No.
2005-323,604, the content of which is incorporated hereinto by
reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a method for patterning a
sacrificial film on or over a wafer, which involves forming a
interconnect pattern including a plurality of parallel straight
lines.
[0004] 2. Related Art
[0005] In recent years, a packing density of semiconductor
integrated circuits is progressed, and a minimum design rule for
circuit elements and interconnects is on the order of sub-100 nm.
This requires a short wavelength light such as KrF or ArF laser in
a photolithographic technology for transferring a pattern of a mask
in a photoresist film on a wafer. Since the short wavelength of the
resolution light is needed, there requires a break through in the
photolithographic technology, and therefore the shrinking in size
of patterns such as interconnect lines including gate electrode
lines becomes difficult.
[0006] A phase shift mask technology, which is capable of
preventing the contrast reduction of a photographic image by
suitably changing a phase of the light transmitted through the
mask, is proposed in order to proceed the scaling of the
semiconductor devices. It is typically known such technology as a
Levenson phase shifting mask, which is called after an inventor M.
D. Levenson.
[0007] FIG. 37 is a plan view of a region containing a corner of
the mask aperture pattern in a conventional phase shifting mask. As
shown in FIG. 37, a Levenson phase shifting mask 500 is configured
that the phase angle of a light passed through one aperture 510 is
different from phase angle of a light passed through other aperture
512 by 180.degree. (n) in a region of a pair of apertures 510 and
512 across an opaque region. This achieves absolutely zero
intensity of light in the opaque region, when an image is formed on
the wafer. In FIG. 37, the aperture 510 for 0.degree. (reference)
transmitted light is shown as a plain region, the aperture 512 for
180.degree. (n) transmitted light is shown as a hatched region, and
the opaque region is shown as a screen-tone region. In addition to
above, such Levenson phase shifting mask 500 includes a peripheral
opaque region 520.
[0008] FIG. 38 is a diagram, illustrating a pattern formed in a
photoresist film after a light exposure by using a phase shifting
mask. As shown in FIG. 38, a photoresist film 600 includes a
portion of an interconnect pattern 602 and other portions, which
should be removed. Thereafter, an additional light exposure process
is conducted by employing a trim mask to expose on above-mentioned
peripheral opaque region 520, so that a final interconnect pattern
602 is formed in the photoresist film 600.
[0009] When the phase shifting mask 500 is employed, some problems
arise such as the reduction or constriction of the line width on
the edge of the pattern as shown in FIG. 38 and FIG. 39. When the
area having the constriction or reduction of the line width is a
gate electrode area, the gate width becomes narrow at the
constriction portion, thereby changing the properties of a metal
oxide semiconductor field effect transistor (MOSFET) from the
designed properties. Therefore, various efforts are made to prevent
such a pattern constriction and a line width reduction.
[0010] A technology for the countermeasures is described in
Japanese Patent Laid-Open No. 2001-42,545. In Japanese Patent
Laid-Open No. 2001-42,545, dark rectangular assist figures are
added to the mask aperture pattern edges in the vicinity of the
corners to increase a width of the interval between the adjacent
apertures, where the interval corresponds to a line width in
photoresist film.
SUMMARY OF THE INVENTION
[0011] Nonetheless, an optical proximity correction (OPC) process
described in Japanese Patent Laid-Open No. 2001-42,545
significantly depends upon various conditions of the mask. While
the appropriate size of the assist pattern features be necessarily
changed in accordance with the wave length of light, numerical
aperture (NA) of optical lens, NA ratio (a) between the optics for
illumination and the optics for image formation or the like, the
appropriate size of the assist pattern features also depends upon
width of the aperture and length of the aperture, so that the size
of the assist pattern features should be properly determined so as
to conform these values related to the mask. As such, the method
described in Japanese Patent Laid-Open No. 2001-42,545 is not
beneficial, since a complex procedure is required for calculating
appropriate sizes of the pattern corresponding to respective sizes
of the interconnect lines, and more shrunken design rule is
required for accurately designing the mask.
[0012] According to one aspect of the present invention, there is
provided a method of forming a pattern, in which an interconnect
pattern including a plurality of straight lines that are arranged
in parallel is formed in the sacrificial film on or over a wafer by
exposing thereof to light through a phase shifting mask, said phase
shifting mask having interconnect apertures that extend toward a
predetermined direction and are arranged in parallel, and said
phase shifting mask also being configured that transmitted lights
of two different phases are alternately assigned in the
interconnect aperture, said method comprising: providing a
different phase aperture in a longitudinal external side of said
interconnect aperture in said phase shifting mask, said different
phase aperture providing a phase of transmitted light that is
different from a phase of light through the interconnect aperture;
transferring a basic pattern in the sacrificial film via an
exposure by using said phase shifting mask, said basic pattern
containing said interconnect pattern and a temporary pattern formed
from an end of said interconnect pattern toward a longitudinal
external side thereof; and transferring a temporary pattern in a
photoresist film for removing said temporary pattern from said
basic pattern via an exposure by using a trim mask.
[0013] The temporary pattern is the portion to be removed at last,
but the pattern is present after first exposure process.
[0014] According to the method for forming pattern according to the
above-described aspect of the invention, the phase shifting mask is
configured that the different phase apertures are arranged with
predetermined spacings therebetween around the width
direction-peripherals of respective interconnect apertures, and the
different phase apertures are arranged with predetermined spacings
therebetween around the longitudinal direction-peripherals of
respective interconnect apertures. More specifically, when a basic
pattern is transferred in the sacrificial film via the exposure
process through the phase shifting mask, respective interconnect
patterns included in the basic pattern exhibit similar optical
conditions both in the longitudinal direction-center and in the
longitudinal direction-end, so that a generation of a constricted
portion in the longitudinal direction-end of the interconnect
pattern be inhibited, thereby providing substantially straight
width direction-peripheral of the interconnect pattern. The
exposure process through the phase shifting mask also provides
forming the temporary pattern in the sacrificial film, in addition
to the respective lines in the interconnect pattern. Thereafter,
the exposure process through the trim mask is conducted to transfer
the trimming pattern in the sacrificial film for removing the
temporary pattern, and then, the temporary pattern is removed to
obtain the interconnect pattern on the sacrificial film.
[0015] In the conventional technology, a line pattern is
constricted around the corner of the aperture, since the optical
condition of the corner of the aperture is different from that in
the center of the aperture. More specifically, a pair of aperture
regions is formed across the opaque region in the central portion
thereof, and the phase of light passed through one aperture is
inverse of the phase of light passed through the other aperture,
and such optical conditions are also achieved around the corner of
the aperture.
[0016] According to the present invention, a creation of the
constricted portion can be inhibited without adding an assist
opaque region in the inside of the aperture on the phase shifting
mask. As a result, a complex procedure is not required to calculate
appropriate aperture sizes for respective line pattern sizes. Here,
concerning the inversed-phase aperture in the phase shifting mask,
a pattern corresponding to such aperture is transferred in the
photoresist film or the hardmask film as at least a portion of the
temporary pattern, and then is eventually removed via the exposure
process through the trim mask. By adding the different phase
aperture the design rule for the phase shifting mask does not
become severe, and thus this technology is extremely advantageous
for the practical use.
BRIEF DESCRIPTION OF THE DRAWING
[0017] The above and other objects, advantages and features of the
present invention will be more apparent from the following
description taken in conjunction with the accompanying drawings, in
which:
[0018] FIG. 1 is a partially-enlarged view of region containing a
corner of a mask pattern of a phase shifting mask according to
first embodiment;
[0019] FIG. 2 is a partially enlarged view of a pattern formed in a
photoresist film after an exposure by using the phase shifting
mask;
[0020] FIG. 3 is a partially enlarged view of a pattern formed in a
photoresist film, illustrating a trimming region removed via a
process employing a trim mask;
[0021] FIG. 4 is a partially enlarged view of a pattern formed in a
photoresist film after an exposure by using the trim mask;
[0022] FIG. 5 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0023] FIG. 6 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0024] FIG. 7 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0025] FIG. 8 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0026] FIG. 9 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0027] FIG. 10 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0028] FIG. 11 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0029] FIG. 12 is a partially enlarged view of a phase shifting
mask, illustrating a configuration according to second
embodiment;
[0030] FIG. 13 is a partially enlarged view of a pattern formed in
a photoresist film after an exposure by using the phase shifting
mask;
[0031] FIG. 14 is a partially enlarged view of a pattern formed in
a photoresist film, illustrating a trimming region removed via a
process employing a trim mask;
[0032] FIG. 15 is a partially enlarged view of a pattern formed in
a photoresist film after an exposure by using the trim mask;
[0033] FIG. 16 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0034] FIG. 17 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0035] FIG. 18 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0036] FIG. 19 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0037] FIG. 20 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0038] FIG. 21 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0039] FIG. 22 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0040] FIG. 23 is a partially enlarged view of a phase shifting
mask, illustrating a configuration according to third
embodiment;
[0041] FIG. 24 is a partially enlarged view of a pattern formed in
a photoresist film after an exposure by using the phase shifting
mask;
[0042] FIG. 25 is an a partially enlarged view of a pattern formed
in a photoresist film, illustrating a trimming region removed via a
process employing a trim mask;
[0043] FIG. 26 is a partially enlarged view of a pattern formed in
a photoresist film after an exposure by using the trim mask;
[0044] FIG. 27 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0045] FIG. 28 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0046] FIG. 29 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0047] FIG. 30 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0048] FIG. 31 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0049] FIG. 32 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0050] FIG. 33 is a partially enlarged view of a phase shifting
mask, illustrating a configuration of a modified embodiment;
[0051] FIG. 34 is a plan view of a phase shifting mask according to
first embodiment;
[0052] FIG. 35 is a plan view of a trim mask;
[0053] FIG. 36 is a plan view of a pattern formed in a photoresist
film after an exposure by using the trim mask;
[0054] FIG. 37 is a partially enlarged view of a conventional phase
shifting mask;
[0055] FIG. 38 is a partially enlarged view of a conventional
pattern formed in a photoresist film after an exposure by using the
phase shifting mask; and
[0056] FIG. 39 is a partially enlarged view of a conventional
pattern formed in a photoresist film after an exposure by using the
trim mask.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0057] The invention will be now described herein with reference to
illustrative embodiments. Those skilled in the art will recognize
that many alternative embodiments can be accomplished using the
teachings of the present invention and that the invention is not
limited to the embodiments illustrated for explanatory
purposed.
[0058] Preferable embodiments of processes for forming pattern
according to the present invention will be described as follows in
further detail, in reference to the annexed figures. In figures,
identical numeral is assigned to an element commonly appeared in
the figures, and redundant descriptions thereof will not be
presented. Further, while hatched lines, dotted lines, screen tone
and the like are drawn for indicating an aperture in a mask in the
respective figures, these are drawn for the purpose of description,
and a portion indicated by hatched lines, dotted lines, screen tone
or the like do not necessarily form a cross section.
First Embodiment
[0059] FIG. 1 to FIG. 4 and FIG. 34 to FIG. 36 illustrate first
embodiment of the present invention, and specifically, FIG. 34 is a
plan view of a phase shifting mask, FIG. 1 is a partially enlarged
view of region containing a corner of a mask pattern of a phase
shifting mask in FIG. 34. FIG. 35 is a plan view of a trim mask.
FIG. 2 is an enlarged plan view of a pattern, which is formed in a
photoresist film after an exposure process through a phase shifting
mask, FIG. 3 is an enlarged plan view of a pattern, which is formed
in the photoresist film, indicating a trimming region to be removed
by a process through a trim mask. FIG. 36 is an enlarged plan view
of a pattern, which is formed in the photoresist film after an
exposure process through the trim mask, and FIG. 4 is a partially
enlarged view of region containing a corner of the pattern in FIG.
36.
[0060] Hereinafter, a method of forming a pattern according to the
present embodiment will be described as a method of forming a
pattern in the region containing a corner of the pattern. In
addition, second or third embodiment will be described as first
embodiment.
[0061] A method of forming a pattern according to the present
embodiment involves forming in a photoresist film 200 applied over
a wafer an interconnect pattern 202 including a plurality of
parallel straight lines as shown in FIG. 4, via an exposure process
through a phase shifting mask 100 shown in FIG. 1. As shown in FIG.
1, a phase shifting mask 100 is provided with apertures 110,112,114
and 116 formed in a light shielding region, through which light
passes, and a pair of different phases is assigned to each of the
apertures 110,112,114 and 116. The pair of different phases is
specifically 0 and n. Further, the phase shifting mask 100 includes
a peripheral opaque region 120, and the peripheral portion thereof
is configured that the pattern is remained in a photoresist film
200 when an exposure process is conducted (see FIG. 2).
[0062] The phase shifting mask 100 is formed to have a
substantially tetragonal plan view, and as shown in FIG. 34. The
region 101 containing a corner of the mask aperture pattern in the
phase shifting mask 100, as shown in FIG. 1, contains a
micro-pattern forming region 102 dedicated to form an interconnect
pattern 202 inside thereof, and a trimming region 104 outside
thereof, where the pattern is removed by a process through a trim
mask as discussed later.
[0063] The micro-pattern forming region 102 includes interconnect
apertures 110 and 112, which extend toward a predetermined
direction (e.g., vertical direction in FIG. 1) and are arranged in
parallel, and two different phases are alternately assigned to the
interconnect apertures 110 and 112. In FIG. 1, the interconnect
aperture 110 of phase 0.degree. is shown as a plain region, the
interconnect aperture 112 of phase .pi. is shown as a lines hatched
region, and the light shielding region including the peripheral
opaque region 120 is shown as a points hatched region, except for
110, 112, 114 and 116.
[0064] As shown in FIG. 1, a trimming region 104 is configured to
overlap the longitudinal end of the respective interconnect
apertures 110 and 112, and a final geometry of longitudinal end of
the interconnect pattern 202 is provided by a trimming. The
longitudinal external side of the respective interconnect apertures
110 and 112 in the trimming region 104 is provided with trimming
region apertures 114 and 116, which exhibits a phase that is
inverse of a phase of each of the interconnect apertures 110 and
112. More specifically, as shown in FIG. 1, the peripheral opaque
region 120 in the phase shifting mask 100 is provided with a
trimming region aperture 114 of phase .pi. corresponding to the
interconnect aperture 110 of phase 0.degree., and a trimming region
aperture 116 of phase 0.degree. corresponding to the interconnect
aperture 112 of phase .pi.. In the present embodiment, the trimming
region apertures 114 and 116 serving as a different phase aperture
are formed to be spaced apart from the interconnect apertures 110
and 112 with a predetermined spacing therebetween through light
shielding region, respectively. Further, the trimming region
apertures 114 and 116 are formed to have widths that are
substantially the same as the widths of the interconnect apertures
110 and 112, respectively, and light shielding regions are disposed
between the adjacent trimming region apertures 114 and 116.
[0065] In the method of forming the pattern of the present
embodiment, an exposure process through the phase shifting mask 100
is conducted. The pattern formed in the exposure process through
the phase shifting mask 100 is composed of an exposed region and an
unexposed region in the photoresist film. And then, without a
photoresist development, an additional exposure process is
conducted through a trim mask 122 containing an exposure region 124
and an opaque region 126, as shown in FIG. 35, in place of the
phase shifting mask, thereby removing a temporary pattern 206 in a
basic pattern 204 formed by a process through the phase shifting
mask 100. A condition of forming the pattern in the photoresist
film 200 employing such method of forming the pattern will be
described in reference to FIG. 2 to FIG. 4. In FIG. 2 to FIG. 4, a
patterned portion formed in the photoresist film via an exposure by
using a mask is indicated as a screen-tone region.
[0066] First of all, a coherent monochrome light flux having a
constant wave length is irradiated over the phase shifting mask
100, so that a light, which have passed through the phase shifting
mask 100, is introduced to a condenser lens system having a
constant NA. The light, which have passed through the condenser
lens system, projects a reduced pattern formed in the phase
shifting mask 100 including the apertures 110, 112, 114 and 116, so
that the basic pattern 204 is transferred in the photoresist film
200 serving as a sacrificial film formed on or over the wafer. This
configuration provides transferring the image including portions
corresponding to the apertures 110, 112, 114 and 116, corners of
which are rounded, as shown in FIG. 2, and the rest of the portions
corresponding to the apertures 110, 112, 114 and 116 forms the
basic pattern 204. The basic pattern 204 is composed of an
unexposed region in the photoresist film formed in the exposure
process through the phase shifting mask 100, and includes the
interconnect pattern 202 and a temporary pattern 206 formed from
the end portion of the interconnect pattern 202 to the longitudinal
external side.
[0067] Here, along the width direction, the interconnect apertures
110 and 112 of different phases are arranged with a predetermined
spacing therebetween, and along the longitudinal direction,
trimming region apertures 114 and 116 of different phases are
arranged with a predetermined spacing therebetween. More
specifically, the longitudinal center of the interconnect pattern
202 exhibits similar optical condition as the optical condition in
the longitudinal-end thereof, so that a generation of a constricted
portion in the longitudinal direction-end of the interconnect
pattern 202 be inhibited, thereby providing substantially uniform
width of the interconnect pattern 202, as shown in FIG. 2.
[0068] Next, the phase shifting mask 100 is replaced with a trim
mask 122, and an exposure process through the trim mask 122 is
conducted. A trimming pattern 208 for removing the pattern 206 in
the basic pattern 204 is transferred in the photoresist film 200 by
conducting such exposure process. In the present embodiment, the
photoresist film, on which the basic pattern 204 is transferred via
the exposure process through the phase shifting mask 100 and the
photoresist film, on which the trimming pattern 208 is transferred
via the exposure process through the trim mask are the same
photoresist mask.
[0069] That is, the temporary pattern 206 unexposed in the exposure
process through the phase shifting mask 100 is exposed by exposure
process through the trim mask 122, and only the interconnect
pattern 202 in the basic pattern 204 remains as the unexposed
region after photoresist development. More specifically, the
peripheral portion in the basic pattern 204 indicated by the region
of the dotted lines in FIG. 3 is removed to form the interconnect
pattern 202 shown in FIG. 4.
[0070] As such, according to the method of forming the pattern of
the present embodiment, the pattern formed in the photoresist film
200 corresponding to the trimming region apertures 114 and 116 is
eventually removed via a trimming by the exposure process through
the trim mask. Thus, longitudinal-end of the interconnect apertures
110 and 112 exhibits similar optical condition as the longitudinal
center thereof, so that a generation of a constricted portion be
inhibited.
[0071] Therefore, a creation of the constricted portion can be
inhibited without a need for adding an assist opaque region in the
inside of the interconnect apertures 110 and 112 in the phase
shifting mask 100, a complex procedure for calculating appropriate
sizes of the pattern 202 corresponding to respective sizes of the
interconnect patterns is not required, and thus a severe design
rule for the phase shifting mask 100 is eased.
[0072] Further, the trimming region apertures 114 and 116 in the
phase shifting mask 100 is transferred in the photoresist film 200
as a portion of the pattern 206 to be removed, and as shown in FIG.
4, is eventually removed via an exposure by using the trim mask.
Therefore, the design rule for the phase shifting mask 100 does not
become severe by the formation of the trimming region apertures 114
and 116. Since the interconnect apertures 110 and 112 have widths
that are substantially the same as the width of the trimming region
apertures 114 and 116 in the present embodiment, the trimming
region apertures 114 and 116 can be formed by applying the design
rule for the interconnect apertures 110 and 112, so that the
formation of the constricted portion in the interconnect pattern be
inhibited, and thus this technology is extremely advantageous on
the occasion for the practical use.
[0073] While the configuration of disposing the light shielding
region interposed between the adjacent trimming region apertures
114 and 116 is illustrated in first embodiment, the adjacent
trimming region apertures 114 and 116 may be continually disposed
as shown in FIG. 5, for example, without disposing the light
shielding region therebetween. In the configuration shown in FIG.
5, trimming region apertures 114 and 116, each of which exhibits a
different phase, are formed to have larger widths than the
corresponding interconnect apertures 110 and 112, respectively. As
described above, maximum width-directional dimensions of the
trimming region apertures 114 and 116 are ensured without providing
a light shielding region, so that generations of distortions in the
interconnect apertures 110 and 112 can be more effectively
inhibited.
[0074] If the apertures of different phases are arranged so as to
be in contact with each other, a defect may possibly be generated
and thus an abnormal resolution pattern may be created, and
consequently it is inhibited to arrange the apertures of different
phases so as to be in contact with each other, in the ordinary
patterning process. Nevertheless, since the entire pattern is
removed in the trimming region 104, obstacles are not created, if
the trimming region apertures 114 and 116 are arranged so as to be
in contact with each other, as shown in FIG. 5.
[0075] While the configuration of disposing the trimming region
apertures 114 and 116 spaced apart from the interconnect apertures
110 and 112 interposing the light shielding region therebetween is
illustrated in first embodiment, at least one of the interconnect
apertures 110 and 112 may be alternatively arranged continually
with the trimming region apertures 114 and 116, which are arranged
in a longitudinal external side of the interconnect apertures 110
and 112, for example, as shown in FIG. 6 to FIG. 11.
[0076] FIG. 6 illustrates a configuration that the interconnect
aperture 112 of phase .pi. is in contact with the trimming region
aperture 116 of phase 0.degree.. In FIG. 6, the interconnect
aperture 112 of phase .pi. is extended toward the longitudinal
external side of the interconnect aperture 110 of phase 0.degree.
so that the interconnect aperture 112 is adjacent to the trimming
region aperture 116 of phase 0.degree.. This configuration provides
an improved linearity of the interconnect pattern 202 formed in the
photoresist film 200. Concerning the interconnect aperture 110 of
phase 0.degree., a light shielding region is interposed with the
trimming region aperture 114 of phase .pi.. Such manner is
advantageous when the interconnect aperture 112 of phase .pi. is
relatively narrow, since sufficient quantity of transmitted light
can be ensured by extending the interconnect aperture 112 of phase
.pi. toward the longitudinal external side thereof.
[0077] While the trimming region apertures 114 and 116 are formed
to have widths, which are substantially the same as the widths of
the interconnect apertures 110 and 112, respectively, and are
disposed across the light shielding region interposed therebetween
in the configuration shown in FIG. 6, the trimming region apertures
114 and 116 may be in contact with each other, as shown in FIG. 7.
Having this configuration, generations of distortions in the
interconnect apertures 110 and 112 can be more effectively
inhibited.
[0078] Further, as shown in FIG. 8, the interconnect aperture 110
of phase 0.degree. may be configured to be in contact with the
trimming region aperture 114 of phase .pi.. In FIG. 8, the
interconnect aperture 110 of phase 0.degree. is extended toward the
longitudinal external side of the interconnect aperture 110 of
phase 0.degree. so that the interconnect aperture 112 is adjacent
to the trimming region aperture 114 of phase .pi.. This
configuration also provides an improved linearity of the
interconnect pattern 202 formed in the photoresist film 200.
Concerning the interconnect aperture 112 of phase .pi., an opaque
region is interposed with the trimming region aperture 116 of phase
0.degree.. Such manner is advantageous when the interconnect
aperture 110 of phase 0.degree. is relatively narrow, since
sufficient quantity of transmitted light can be ensured by
extending the interconnect aperture 110 of phase 0.degree. toward
the longitudinal external side thereof.
[0079] While the trimming region apertures 114 and 116 are formed
to have widths, which are substantially the same as the widths of
the interconnect apertures 110 and 112, respectively, and are
disposed across the light shielding region interposed therebetween
in the configuration shown in FIG. 8, the trimming region apertures
114 and 116 may be in contact with each other, as shown in FIG. 9.
Having this configuration, generations of distortions in the
interconnect apertures 110 and 112 can be more effectively
inhibited.
[0080] Further more, as shown in FIG. 10, both the interconnect
aperture 110 of phase 0.degree. and the interconnect aperture 112
of phase .pi. may be configured to be in contact with the trimming
region apertures 114 and 116, respectively. In FIG. 10, all the
interconnect apertures 110 and 112 are extended toward the
longitudinal external side thereof, so that these interconnect
apertures are adjacent to the trimming region apertures 114 and
116. This configuration also provides an improved linearity of the
interconnect pattern 202 formed in the photoresist film 200. While
the trimming region apertures 114 and 116 are formed to have
widths, which are substantially the same as the widths of the
interconnect apertures 110 and 112, respectively, and are disposed
across the light shielding region interposed therebetween in the
configuration shown in FIG. 10, the trimming region apertures 114
and 116 may be in contact with each other, as shown in FIG. 11.
[0081] Having this configuration, generations of distortions in the
interconnect apertures 110 and 112 can be more effectively
inhibited.
Second Embodiment
[0082] FIG. 12 to FIG. 15 illustrate second embodiment of the
present invention, and specifically, FIG. 12 is a partially
enlarged view of region containing a corner of a mask pattern of a
phase shifting mask, FIG. 13 is a partially enlarged plan view of
region containing a corner of a pattern, which is formed in a
photoresist film after an exposure process through a phase shifting
mask, FIG. 14 is a partially enlarged plan view of region
containing a corner of a pattern, which is formed in the
photoresist film, indicating a trimming region to be removed by a
process through a trim mask, and FIG. 15 is a partially enlarged
plan view of region containing a corner of a pattern, which is
formed in the photoresist film after an exposure process through
the trim mask.
[0083] A method of forming a pattern according to the present
embodiment involves forming in a photoresist film 200 applied over
a wafer an interconnect pattern 212 including a plurality of
parallel straight lines, via an exposure process through a phase
shifting mask 300 shown in FIG. 12. The configuration of the phase
shifting mask 300 is same as the configuration of the phase
shifting mask 100 of first embodiment, except that a peripheral
thereof is an exposure region. More specifically, the phase
shifting mask 300 includes a peripheral exposure region 320, and
the peripheral portion thereof is configured that no pattern is
formed in the photoresist film 200 via the exposure process (see
FIG. 13).
[0084] As shown in FIG. 12, in region 301 containing a corner of a
mask pattern of the phase shifting mask 300, the inside region
thereof includes a micro-pattern forming region 302 for forming an
interconnect pattern 212. A trimming region 304 is configured to
overlap the longitudinal end of the interconnect apertures 310 and
312, and is disposed in a longitudinal outer peripherals of the
interconnect apertures 310 and 312. Similarly as in first
embodiment, the longitudinal external side of the respective
interconnect apertures 310 and 312 in the trimming region 304 is
provided with trimming region apertures 314 and 316, which exhibits
a phase that is inverse of a phase of each of the interconnect
apertures 310 and 312. In the present embodiment, the longitudinal
external side of the interconnect apertures 310 and 312 serves as
an assist opaque region 322, and the assist opaque region 322 of
the peripheral exposure region 320 is provided with a trimming
region aperture 314 of phase .pi. corresponding to the interconnect
aperture 310 of phase 0.degree., and a trimming region aperture 316
of phase 0.degree. corresponding to the interconnect aperture 312
of phase .pi..
[0085] In the method of forming the pattern of the present
embodiment, an exposure process through the phase shifting mask 300
is conducted, and then, an additional exposure process is conducted
through a trim mask (not shown) in place of the phase shifting
mask, thereby removing a temporary pattern 216 in a basic pattern
214 formed by a process through the phase shifting mask 300. A
condition of forming the pattern in the photoresist film 200
employing such method of forming the pattern will be described in
reference to FIG. 13 to FIG. 15.
[0086] In the present embodiment, the exposure process through the
phase shifting mask 300 provides transferring the image including
portions corresponding to the apertures 310, 312, 314 and 316 and
an exposed region of the peripheral thereof, corners of which are
rounded, as shown in FIG. 13, and the rest of the portions
corresponding to the apertures 310, 312, 314 and 316 and the
exposed region of the peripheral thereof forms the basic pattern
214. The basic pattern 214 includes the interconnect pattern 212
and a temporary pattern 216 formed from the end portion of the
interconnect pattern 212 to the longitudinal external side.
[0087] Here, along the width direction, the interconnect apertures
310 and 312 of different phases are arranged with a predetermined
spacing therebetween, and along the longitudinal direction,
trimming region apertures 314 and 316 of different phases are
arranged with a predetermined spacing therebetween. More
specifically, the longitudinal center of the interconnect pattern
212 exhibits similar optical condition as the optical condition in
the longitudinal-end thereof, so that a generation of a constricted
portion in the longitudinal direction-end of the interconnect
pattern 212 be inhibited, thereby providing substantially straight
width direction-peripheral of the interconnect pattern 212, as
shown in FIG. 13.
[0088] Next, the phase shifting mask 300 is replaced with a trim
mask, and an exposure process through the trim mask is conducted. A
trimming pattern 218 for removing the pattern 216 to be removed is
transferred by conducting such exposure process. More specifically,
an outer side from the longitudinal end of the interconnect pattern
212 in the basic pattern 214 shown as a region of dotted lines in
FIG. 14 is removed to form the interconnect pattern 212 shown in
FIG. 15.
[0089] As such, according to the method of forming the pattern of
the present embodiment, the pattern formed in the photoresist film
200 corresponding to the trimming region apertures 314 and 316 is
eventually removed via a trimming by the exposure process through
the trim mask. Thus, longitudinal-end of the interconnect apertures
310 and 312 exhibits similar optical condition as the longitudinal
center thereof, so that a generation of a constricted portion be
inhibited.
[0090] In the present embodiment, the peripheral exposure region
320 in the phase shifting mask 300 exhibits phase 0.degree., and
resolution of the pattern may be easily influenced by an external
leaked light around the apertures 310 and 316 of phase 0.degree. in
the phase shifting mask 300, which are adjacent to the peripheral
exposure region 320. However, since the trimming region aperture
314 of phase .pi. is arranged in a longitudinal external side of
the interconnect aperture 310 of phase 0.degree., the interconnect
aperture 310 is not influenced by the exposure region of the
periphery thereof. Further, while the formed pattern is distorted
by the influence of leaked light as shown in FIG. 13 since the
trimming region aperture 316 of phase 0.degree. is adjacent to the
exposure region of the periphery thereof, the distorted pattern is
eventually trimmed via the exposure process through the trim mask,
and therefore there is no obstacle.
[0091] While the configuration of disposing the light shielding
region interposed between the adjacent trimming region apertures
314 and 316 is illustrated in second embodiment, the adjacent
trimming region apertures 314 and 316 may be continually disposed
as shown in FIG. 16, for example, without disposing the light
shielding region therebetween. In the configuration shown in FIG.
16, trimming region apertures 314 and 316, each of which exhibits a
different phase, are formed to have larger widths than the
corresponding interconnect apertures 310 and 312, respectively. As
described above, maximum width-directional dimensions of the
trimming region apertures 314 and 316 are ensured without providing
a light shielding region, so that generations of distortions in the
interconnect apertures 310 and 312 can be more effectively
inhibited.
[0092] While the configuration of disposing the trimming region
apertures 314 and 316 spaced apart from the interconnect apertures
310 and 312 interposing the light shielding region therebetween is
illustrated in second embodiment, at least one of the interconnect
apertures 310 and 312 may be alternatively arranged continually
with the trimming region apertures 314 and 316, which are arranged
in a longitudinal external side of the interconnect apertures 310
and 312, for example, as shown in FIG. 17 to FIG. 22.
[0093] FIG. 17 illustrates a configuration that the interconnect
aperture 312 of phase .pi. is in contact with the trimming region
aperture 316 of phase 0.degree.. In FIG. 17, the interconnect
aperture 312 of phase .pi. is extended toward the longitudinal
external side of the interconnect aperture 310 of phase 0.degree.
so that the interconnect aperture 312 is adjacent to the trimming
region aperture 316 of phase 0.degree.. This configuration provides
an improved linearity of the interconnect pattern 212 formed in the
photoresist film 200. Concerning the interconnect aperture 310 of
phase 0.degree., a light shielding region is interposed with the
trimming region aperture 314 of phase .pi.. Such manner is
advantageous when the interconnect aperture 312 of phase .pi. is
relatively narrow, since sufficient quantity of transmitted light
can be ensured by extending the interconnect aperture 312 of phase
.pi. toward the longitudinal external side thereof.
[0094] While the trimming region apertures 314 and 316 are formed
to have widths, which are substantially the same as the widths of
the interconnect apertures 310 and 312, respectively, and are
disposed across the light shielding region interposed therebetween
in the configuration shown in FIG. 17, the trimming region
apertures 314 and 316 may be in contact with each other, as shown
in FIG. 18. Having such configuration, generations of distortions
in the interconnect apertures 310 and 312 can be more effectively
inhibited.
[0095] Further, as shown in FIG. 19, the interconnect aperture 310
of phase 0.degree. may be configured to be in contact with the
trimming region aperture 314 of phase .pi.. In FIG. 19, the
interconnect aperture 310 of phase 0.degree. is extended toward the
longitudinal external side of the interconnect aperture 312 of
phase .pi. so that the interconnect aperture 310 is adjacent to the
trimming region aperture 314 of phase .pi.. This configuration also
provides an improved linearity of the interconnect pattern 212
formed in the photoresist film 200. Concerning the interconnect
aperture 312 of phase .pi., a light shielding region is interposed
with the trimming region aperture 316 of phase 0.degree.. Such
manner is advantageous when the interconnect aperture 310 of phase
0.degree. is relatively narrow, since sufficient quantity of
transmitted light can be ensured by extending the interconnect
aperture 310 of phase 0.degree. toward the longitudinal external
side thereof.
[0096] While the trimming region apertures 314 and 316 are formed
to have widths, which are substantially the same as the widths of
the interconnect apertures 310 and 312, respectively, and are
disposed across the light shielding region interposed therebetween
in the configuration shown in FIG. 19, the trimming region
apertures 314 and 316 may be in contact with each other, as shown
in FIG. 20. Having this configuration, generations of distortions
in the interconnect apertures 310 and 312 can be more effectively
inhibited.
[0097] Further more, as shown in FIG. 21, both the interconnect
aperture 310 of phase 0.degree. and the interconnect aperture 312
of phase .pi. may be configured to be in contact with the trimming
region apertures 314 and 316, respectively. In FIG. 21, all the
interconnect apertures 310 and 312 are extended toward the
longitudinal external side thereof, so that these interconnect
apertures are adjacent to the trimming region apertures 314 and
316. This configuration also provides an improved linearity of the
interconnect pattern 212 formed in the photoresist film 200. While
the trimming region apertures 314 and 316 are formed to have
widths, which are substantially the same as the width of the
interconnect apertures 310 and 312, respectively, and are disposed
across the light shielding region interposed therebetween in the
configuration shown in FIG. 21, the trimming region apertures 314
and 316 may be in contact with each other, as shown in FIG. 22.
Having this configuration, generations of distortions in the
interconnect apertures 310 and 312 can be more effectively
inhibited.
Third Embodiment
[0098] FIG. 23 to FIG. 26 illustrate third embodiment of the
present invention, and specifically, FIG. 23 is a partially
enlarged view of region containing a corner of a mask pattern of a
phase shifting mask, FIG. 24 is a partially enlarged plan view of
region containing a corner of a pattern, which is formed in a
photoresist film after an exposure process through a phase shifting
mask, FIG. 25 is a partially enlarged plan view of region
containing a corner of a pattern, which is formed in the
photoresist film, indicating a trimming region to be removed by a
process through a trim mask, and FIG. 26 is a partially enlarged
plan view of region containing a corner of a pattern, which is
formed in the photoresist film after an exposure process through
the trim mask.
[0099] A method of forming a pattern according to the present
embodiment involves forming in a photoresist film 200 applied over
a wafer an interconnect pattern 222 including a plurality of
parallel straight lines, via an exposure process through a phase
shifting mask 400 shown in FIG. 23. The phase shifting mask 400 is
configured that a peripheral thereof is an exposure region,
similarly as in the configuration of the phase shifting mask 200 of
second embodiment. More specifically, the phase shifting mask 400
includes a peripheral exposure region 420, and the peripheral
portion thereof is configured that no pattern is formed in the
photoresist film 200 via the exposure process (see FIG. 24). In
addition to above, the peripheral exposure region 420 exhibits
phase 0.degree., which is one of the two different phases.
[0100] As shown in FIG. 23, in region 401 containing a corner of a
mask pattern of the phase shifting mask 400, the inside region
thereof includes a micro-pattern forming region 402 for forming an
interconnect pattern 222. A trimming region 404 is configured to
overlap the longitudinal end of the interconnect apertures 310 and
312, and is disposed in a longitudinal outer peripherals of the
interconnect apertures 410 and 412.
[0101] Here, unlikely as the second embodiment, the longitudinal
external side of the interconnect aperture 412 of phase .pi. in the
trimming region 404 is provided with no trimming region aperture of
different phase, but provided with a peripheral exposure region
420, interposing a light shielding region having a predetermined
dimension therebetween. Since the phase of the peripheral exposure
region 420 is 0, the aperture serves as a different phase aperture
over the interconnect aperture 412 around the longitudinal side of
the interconnect aperture 412 of phase .pi..
[0102] Further, a trimming region aperture 414 of different phase
.pi. is provided in a longitudinal external side of the
interconnect aperture 410 of phase 0.degree.. In the present
embodiment, the longitudinal external side of the interconnect
aperture 410 of phase 0.degree. serves as an assist opaque region
422, and the assist opaque region 422 is provided with a trimming
region aperture 414 of phase .pi. corresponding to the interconnect
aperture 410 of phase 0.degree.. More specifically, a longitudinal
external side of the interconnect aperture 410 of phase 0.degree.
protrudes to enter into the peripheral exposure region 420.
[0103] In the method of forming the pattern of the present
embodiment, an exposure process through the phase shifting mask 400
is conducted, and then, an additional exposure process is conducted
through a trim mask (not shown) in place of the phase shifting
mask, thereby removing a temporary pattern 226 in a basic pattern
224 formed by a process through the phase shifting mask 400. A
condition of forming the pattern in the photoresist film 200
employing such method of forming the pattern will be described in
reference to FIG. 24 to FIG. 26.
[0104] In the present embodiment, the exposure process through the
phase shifting mask 400 provides transferring the image including
portions corresponding to the apertures 410, 412 and 414 and an
exposed region of the peripheral thereof, corners of which are
rounded, as shown in FIG. 24, and the rest of the portions
corresponding to the apertures 410, 412 and 414 and the exposed
region of the peripheral thereof forms the basic pattern 224.
[0105] Here, along the width direction, the interconnect apertures
410 and 412 of different phases are arranged with a predetermined
spacing therebetween, and along the longitudinal direction of the
interconnect apertures 410, trimming region aperture 414 is
arranged. More specifically, the longitudinal center of the
interconnect pattern 222 exhibits similar optical condition as the
optical condition in the longitudinal-end thereof, so that a
generation of a constricted portion in the longitudinal
direction-end of the interconnect pattern 222 be inhibited, thereby
providing substantially uniform width direction-peripheral of the
interconnect pattern 222, as shown in FIG. 24.
[0106] Next, the phase shifting mask 400 is replaced with a trim
mask 122, and an exposure process through the trim mask 122 is
conducted. A trimming pattern 228 for removing the pattern 226 to
be removed is transferred by conducting such exposure process. More
specifically, an outer side from the longitudinal end of the
interconnect pattern 222 in the basic pattern 224 shown as a region
of dotted lines in FIG. 25 is removed to form the interconnect
pattern 222 shown in FIG. 26.
[0107] As such, according to the method of forming the pattern of
the present embodiment, the pattern formed in the photoresist film
200 corresponding to the trimming region aperture 414 is eventually
removed via a trimming by the exposure process through the trim
mask. Thus, longitudinal-end of the interconnect apertures 410 and
412 exhibits similar optical condition as the longitudinal center
thereof, so that a generation of a constricted portion would be
inhibited.
[0108] In the present embodiment, the peripheral of the phase
shifting mask 400 is an exposure region of phase 0.degree., and
resolution of the pattern may be easily influenced by an external
leaked light, if an aperture 410 of phase 0.degree. in the phase
shifting mask 400 approaches the exposure region. However, since
the trimming region aperture 414 of phase .pi. is arranged in a
longitudinal external side of the interconnect aperture 410 of
phase 0.degree., the interconnect aperture 410 is not influenced by
the exposure region of the peripheral thereof.
[0109] Further, since the exposure region in the peripheral thereof
serves as a different phase aperture against the interconnect
aperture 412 of phase .pi., a light shielding region can be
omitted, and thus a benefit of providing an increased design
allowance by the size of the omitted region can be achieved.
[0110] While the configuration of disposing the light shielding
region interposed between the trimming region apertures 414 and the
exposure region is illustrated in third embodiment, the trimming
region apertures 414 and the exposure region may be continually
disposed as shown in FIG. 27, for example, without disposing the
light shielding region therebetween.
[0111] While the configuration of disposing the trimming region
aperture 414 of phase .pi. spaced apart from the interconnect
aperture 410 of phase 0.degree. interposing the light shielding
region therebetween and disposing the interconnect aperture 412 of
phase .pi. spaced apart from the exposure region interposing the
light shielding region therebetween is illustrated in third
embodiment, the trimming region aperture 414 and interconnect
aperture 410 may be alternatively arranged to contact with at least
one of the exposure region and the interconnect aperture 412 for
example, as shown in FIG. 28 to FIG. 32.
[0112] FIG. 28 illustrates a configuration that the interconnect
aperture 412 of phase .pi. is in contact with the exposure
region.
[0113] In FIG. 28, the interconnect aperture 412 of phase .pi. is
extended toward the longitudinal external side of the interconnect
aperture 410 of phase 0.degree. so that the interconnect aperture
412 is adjacent to the exposure region. This configuration provides
an improved linearity of the interconnect pattern 222 formed in the
photoresist film 200. Concerning the interconnect aperture 410 of
phase 0.degree., a light shielding region is interposed with the
trimming region aperture 414 of phase .pi.. Such manner is
advantageous when the interconnect aperture 412 of phase .pi. is
relatively narrow, since sufficient quantity of transmitted light
can be ensured by extending the interconnect aperture 412 of phase
.pi. toward the longitudinal external side thereof.
[0114] While the trimming region aperture 414 of phase .pi. is
formed to have a width that is substantially the same as the width
of the interconnect aperture 410 of phase 0.degree., and is
disposed interposing the light shielding region with the exposure
region in the configuration shown in FIG. 28, the trimming region
aperture 414 may be in contact with the exposure region, as shown
in FIG. 29. Having this configuration, a generation of a distortion
in the interconnect aperture 412 of phase .pi. can be more
effectively inhibited.
[0115] Further more, as shown in FIG. 30, the interconnect aperture
410 of phase 0.degree. may be in contact with the trimming region
aperture 414 of phase .pi.. In FIG. 30, the interconnect aperture
410 of phase 0.degree. is extended toward the longitudinal external
side of the interconnect aperture 412 of phase .pi. so that the
interconnect aperture 410 is adjacent to the trimming region
aperture 414 of phase .pi.. This configuration also provides an
improved linearity of the interconnect pattern 222 formed in the
photoresist film 200. Concerning the interconnect aperture 412 of
phase .pi., a light shielding region is interposed with the
exposure region. Such manner is advantageous when the interconnect
aperture 410 of phase 0.degree. is relatively narrow, since
sufficient quantity of transmitted light can be ensured by
extending the interconnect aperture 410 of phase 0.degree. toward
the longitudinal external side thereof.
[0116] While the trimming region aperture 414 of phase .pi. is
formed to have a width that is substantially the same as the width
of the interconnect aperture 410 of phase 0.degree., and is
disposed interposing the light shielding region between the
trimming region aperture 414 and the exposure region in the
configuration shown in FIG. 30, the trimming region aperture 414
may be in contact with the exposure region, as shown in FIG. 31.
Having this configuration, generations of distortions in the
interconnect apertures 410 and 412 can be more effectively
inhibited.
[0117] Further more, as shown in FIG. 32, the interconnect aperture
410 of phase 0.degree. may be in contact with the trimming region
aperture 414 and the interconnect aperture 412 of phase .pi. may be
in contact with the exposure region. In FIG. 32, all the
interconnect apertures 410 and 412 are extended toward the
longitudinal external side thereof so that the interconnect
aperture 410 is adjacent to the trimming region aperture 414 or the
exposure region. This configuration also provides an improved
linearity of the interconnect pattern 222 formed in the photoresist
film 200. While the trimming region aperture 414 is formed to have
a width that is substantially the same as the width of the
interconnect aperture 410, and is disposed interposing the light
shielding region with the exposure region in the configuration
shown in FIG. 32, the trimming region aperture 414 may be disposed
to be adjacent to the exposure region, as shown in FIG. 33.
[0118] Having this configuration, generations of distortions in the
interconnect apertures 410 and 412 can be more effectively
inhibited.
[0119] While the exemplary implementations of so-called dual
exposure for simultaneously removing the basic pattern 204, 214 or
224 via the exposure process through the trim mask have been
illustrated in first to third embodiments, the interconnect pattern
may be obtained by an alternative process, in which, for example,
an exposure process through the phase shifting mask 100, 300 or 400
is conducted and only a hard mask layer is etched, and then, an
exposure process through a trim mask and a hard mask layer and a
target layer are removed. More specifically, the alternative
process may be configured that a sacrificial film includes: a hard
mask formed on or over a wafer; a first photoresist film employed
for etching the hard mask; and a second photoresist film applied on
the wafer after the hard mask is etched through the first
photoresist film, and the basic pattern is transferred onto the
first photoresist film via an exposure process through the phase
shifting mask, and the trimming pattern is transferred onto the
second photoresist film via an exposure process through the trim
mask, after the hard mask is etched through a mask of the first
photoresist film, on which the basic pattern is transferred.
[0120] Further, it should be noted that wave length of light
employed in the exposure process, numerical aperture (NA) of
optical lens, NA ratio (.sigma.) of lighting system and imaging
system, widths of the interconnect apertures 110, 112, 310, 312,
410 and 412, and lengths of the interconnect apertures 110, 112,
310, 312, 410 and 412 can be suitably modified, and specific
detailed structure or the like can be suitably modified.
[0121] It is apparent that the present invention is not limited to
the above embodiment, and may be modified and changed without
departing from the scope and spirit of the invention.
[0122] This invention is a method of forming a pattern including a
fine line pattern in a sacrificial film such as a photorest film or
a hard mask film. The pattern in the sacrificial film is
transferred to an underlying film after dry etching process. The
underlying film is metal, silicon, or dielectric materials, for
example. Here, the pattern including a fine line pattern could be
various interconnections in semiconductor device including gate
electrode.
* * * * *